
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
    <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
    <title>Document</title>
    <style type="text/css">
        *{
            margin: 0;
            padding: 0;
        }
        .all{
            border: 1px solid red;
            line-height: 44px;
            height: 44px;
            display: flex;
        }
        .left,.right{
            width: 60px;
            border: 1px solid black;
        }.middle{
            flex: 1;
        }
    </style>
</head>
<body>
<div class="all">
    <div class="left"></div>
    <div class="middle"></div>
    <div class="right"></div>
</div>
</body>
</html>